Fast Living Polymerization of Challenging Arylisocyanides Using Air-Stable Nickel (II) Initiator Containing Bidentate Phosphine Ligand

Abstract

We report efficient living polymerizations of challenging electron-rich or sterically hindered arylisocyanides using an air-stable but highly active bisphosphine-chelated nickel (II) complex. Initially, the living character was examined by screening various Ni (II) complexes, and we identified o-Tol(dppe)NiCl (C) as an excellent initiator for this purpose. Based on the chain extension experiments and in-situ 31P NMR spectroscopy, we concluded that its high stability of the propagating species due to the tightly bound chelating ligand, was crucial for successful living polymerizations. Not only reactive electron-poor arylisocyanides, but also more challenging electron-rich or sterically hindered arylisocyanides underwent fast living polymerizations to give polymers having controlled Mn with narrow dispersity. In addition, we confirmed that the electronic character of the monomer significantly affects the polymerization efficiency, by comparing the polymerization between 4-octyloxyphenylisocyanide and 3-octyloxyphenylisocyanide, which have the same substituents at the different positions on the phenyl ring. Furthermore, ABCDE pentablock copolymer containing various substituents was efficiently synthesized in only one minute.